Dipper tooth assembly



Jan. 19, 1960 E. G. OPSAHL DIPPER TOOTH ASSEMBLY 4 Sheets-Sheet 1 Filed July 6, 1955 fiINVENTOR. flaw/ W Qdz i zessx WMM Jan. 19, 1960 E. G. OPSAHL 2,921,391

DIPPER TOOTH ASSEMBLY A 4 Sheets-Sheet 2 Filed July 6, 1955 INVENTOR.

2,921,391 1C3 t a Jan. 19, teen DIPPER TOOTH ASSEMBLY Application July 6, 1955, Serial No. 520,229

Claims. c1. 37-142 This invention relates to dipper teeth for excavating equipment and more particularly to a dipper tooth assembly comprising a base and a point in telescopic relationship with each other.

The invention comprehends a dipper tooth assembly comprising a substantially hollow point capped over a base.

It is well known to those familiar with the art of excavating equipment that dipper teeth normally are subjected to such severe and continual abrasive action that their service life is usually of relatively short duration. Because their frequent replacement is necessary as well as expensive, nowadays they are usually made in two parts, a permanent base and throw-away point. However, even with two-piece dipper teeth, the cost of replacing points is still an extremely important factor in excavating operations.

It has been discovered that in normal use the forward edge of a dipper tooth point becomes rounded with a wear pattern contour which is substantially arcuate, as seen from the side of the tooth and substantially semielliptical, as seen from above or below the tooth. Thus because the contour of the forward outer surface of a worn point is curved while its inner base engaging surface is straight, there remains a substantial quantity of material left in the point after its service life has been exhausted.

It is, therefore, an important general object of this invention to provide a dipper tooth point having a base and a substantially hollow throw-away point capped on the base, wherein the inner surfaceof the point cavity, as well as the forward surface of the base, conforms generally to the wear pattern of the outer surface of the point, so that as the point wears down, its inner and outer surfaces will tend to become parallel leaving a minimum quantity of material remaining in the point.

A more specific object of the invention is to provide a two-piece dipper tooth, comprising mating parts which have corresponding surfaces conforming to the general wear pattern of dipper teeth, the surfaces being substantially arcuate as seen in elevation, and substantially semielliptical as seen in plan.

Although every two-piece dipper tooth assembly is provided with a primary means to secure the point to the base, such as a wedge key and slot arrangement, it is highly desirable to have a secondary securing means in the event of failure of the primary securing means. It has been discovered that in the event of such failure, the point will tend to slide forwardly down and oif the end of the base because the corresponding surfaces of both the point and base slope toward the forward edge of the point and nothing resists such separation.

It is therefore another important general object of the invention to provide a dipper tooth assembly having at least one pair of fiat parallel surfaces on the base and point which are engageable to prevent their separation in the event of failure of the primary securing means.

A more specific object of the invention is the provision of a dipper tooth assembly wherein the parallel retaining surfaces are provided on a shelf recessed in the central portion of the base.

Another specific object is the provision of a dipper tooth assembly wherein the parallel retaining surfaces are provided on shelves of the point and in grooves in the sides of the base.

Still another specific object is the provision of a dipper tooth assembly wherein the retaining surfaces are parallel to the lower surfaces of the point and base.

These and other objects of the invention will be apparent from an examination of the following description and drawings, wherein:

Figure 1 is a plan view of a dipper tooth assembly embodying the invention;

Figure 2 is a side elevational view of the structure shown in Figure 1;

Figure 3 is a sectional view taken along the line 3-3 of Figure 2;

Figure 4 is an exploded perspective view of the structure illustrated in Figure 1;

Figure 5 is a fragmentary sectional view of a conventional dipper tooth point;

Figure 6 is a fragmentary sectional view of a dipper tooth point embodying the invention;

Figure 7 is a view similar to Figure 1, but illustrating another embodiment of the invention;

Figure 8 is a sectional view taken along line 8-8 of Figure 7;

vFigures 9-11 are sectional views taken along 9-9, 10-10 and 11-11, respectively, of Figure 8;

Figure 12 is a view similar to Figure 1 but illustrating still another embodiment of the invention;

Figure 13 is a fragmentary side elevational view of the structure illustrated in Figure 12, and

Figures 14 and 15 are sectional views taken along the lines 14-14 and 15-15, respectively, of Figure 13.

It will be apparent that certain elements have been intentionally omitted from certain figures where they are illustrated to better advantage in other views.

Referring now to the drawings for a better understanding of the invention, it will be seen that the dipper tooth assembly, illustrated in Figures 1-4, which embodies one form of my invention comprises a base, indicated generally at 10, and a point, indicated generally at 12, which are adapted for telescopic engagement with each other. It will be noted that because the base and the point are symmetrical about the transverse center plane P-P of the base nose, they are individually reversible.

The base, as best seen in Figures 1 and 2, comprises spaced upper and lower jaws 14 and 16, respectively, which diverge rearwardly to form a recess 18 therebetween. The rearward portions of the jaws may be provided with slots, or grooves 20' to accommodate their attachment to a scoop or bucket (not shown) of an.

excavating machine.

Forwardly of the base, the jaws merge with each other to form a nose section 22, which presents forwardly sloping upper and lower inclined surfaces 24 and 26, respectively, and spaced substantially parallel side surfaces 28 which blend with the upper and lower surfaces to form a forward edge surface 30. The side surfaces are substantially normal to the transverse center plane 19-1? of the base.

The surface 31} of the forward edge of the nose is curved to simulate the wear pattern of dipper teeth points. This curve is semielliptical, as seen in plan, and the radius X of its center section is substantially larger than the radius Y of each end section. In the embodimerit illustrated the ratio of X radius to Y radius is approximately five to one. The curve of the surface 30, as seen in elevation, is substantially arcuate having a radius Z, which in the embodiment illustrated is approximately equal to radius Y.

The nose 22 may be provided with a shelf 32 recessed, or inset, from the upper and lower sloping surfaces 24 and 26, respectively. The shelf 32 presents spacedtop and bottom surfaces 34 and 36, respectively, which are substantially parallel to each other and to the transverse center plane P of the nose. g

It will be observed that the point 12 is also substantially wedge shaped and presents outer forwardly sloping inclined upper and lower surfaces 40 and 42, respectively, and parallel side surfaces 44, which merge to form a forward edge 46 which is generally straight as seen in plan and slightly rounded as seen in side elevation.

The point has a wedge shaped cavity 48, which is adapted to receive the nose 22 of the base. The cavity presents upper and lower forwardly sloping inclined surfaces 50 and 52, respectively, and substantially parallel side surfaces 54 which merge to form a forward edge surface 56. It will be noted that the upper and lower surfaces 50 and 52, respectively, of the cavity correspond to and mate with surfaces 24 and 26, respectively, of nose portion 22. Additionally the point is provided with upper and lower ledges 58 and 60, respectively, which present substantially flat top and bottom spaced surfaces 62 and 64, respectively, in the point cavity 48 which are parallel to each other and to the surfaces 34 and 36 of the nose shelf 32. The outer surfaces 40 and 42 of the point may be provided with recesses 66 where the ledges are set in, if desired, to protect the securing means as hereinafter described.

The shelf 32 of the nose and the ledges 58 and 60 of the point may be provided with coaligned slots 68 and 70, respectively, extending therethrough in a plane normal to the transverse center plane PP of the base nose. By providing the forward wall 65 of the base nose slot 68 with upper and lower rearwardly tapered surfaces 67 and 69, respectively, which converge at the transverse center plane PP of the base nose, the base is made reversible because either surface 67 or surface 69 will be engageable with the upper portion of the forward tapered wall 71 of wedge key 72. It will be seen that in order to assemble the tooth, the cap is inserted over the base with the base nose received in the point cavity, and a wedge key 72 is inserted through the coaligned slots 68 and 70, contacting the upper surface of the forward wall 65 of nose slot 68 and the rear walls 73 of point slots 70.

In Figure 5 the lines of a conventional dipper tooth point are illustrated. The outer or wear surface is indicated by line A and the inner surface, where the point engages the base, by line B. The line C represents the contour of the wear surface A, as seen in plan at the end of the wear life of the point. The letter D represents the amount of wear at the central portion of the point, and letters E and F represent the amount of material remaining in the tooth at the outer edges and central section of the inner surface of the point.

In Figure 6 the lines of a dipper tooth point embodying the invention are illustrated, and corresponding letters have been used to designate corresponding surfaces and distances. However, it will be noted that the contour of the inner surface indicated by B in Figure 6 corresponds to the contour of the wear pattern of the outer surface indicated by C so that at the end of the wear life of the point its inner and outer surfaces are substantially parallel. Thus it will be understood that the amount of the material left in the point of Figure 6 is the same in the center, as indicated by F, as at the edges of the inner surface, indicated by E; whereas, in the conventional point, illustrated in Figure 5, a much greater amount of material, as indicated by F, remains in the center portion of the Worn tooth than at the outer edges of the inner surface. The difference between F and F', therefore, represents the quantity of material wasted, or thrown 4 away, at the end of the wear life of a conventional dipper tooth point.

In the event the nose pulls partially out of the cavity to angle slightly with respect to the point, the top or bottom corresponding parallel surfaces of the shelf and ledge become firmly engaged and further separation is restricted.

Thus it will be seen that the respective fiat parallel surfaces of the shelf and point provide an additional safety feature, as they tend to help maintain the base and point in firm telescopic relationship with each other in the event the wedge key should become lost or broken.

Another embodiment of my invention is illustrated in Figures 7-11 in which similar numerals have been employed to designate elements corresponding to the elements of the above described embodiment. This second embodiment is similar to the first described embodiment in that the forward surface of the base nose, as well as that of the point cavity, has a contour which conforms generally to the normal wear pattern of dipper teeth.

However, although the second embodiment, as well as the third embodiment described below, is not completely symmetrical and therefore not reversible, its main difference from the first embodiment resides in the location of the parallel retaining surfaces. Referring again to Figure 7, it will be seen that the sides 154 of the cavity are provided with inwardly projecting shelves 132 having spaced upper and lower surfaces 134 and 136, respectively, which are parallel to each other and to the transverse center plane of the nose indicated by line PP. The sides 128 of the nose are provided with grooves 158 which receive the shelves 132 of the point. The grooves 158 present spaced flat parallel upper and lower surfaces 162 and 164, respectively, which are engageable with shelf surfaces 134 and 136. Thus the engagement be tween the surfaces of the shelves and grooves, in the event of failure of the primary securing means, serves to retain the base and point in engagement with each other to prevent their separation.

A third embodiment of my invention is illustrated in Figures 12-15 wherein similar numerals have been employed to illustrate elements corresponding to those of the first described embodiment. This embodiment also comprises a two-piece dipper tooth assembly wherein the forward surfaces of the base nose and the point cavity present contour which conforms generally to the normal wear pattern of dipper teeth.

A recessed shelf 232 is provided in the upper portion of the base nose which presents a fiat surface 234 parallel to the lower surfaces 242 and 252 of the point and lower surface 226 of the base nose, respectively.

The upper portion of the point cavity is provided with a depending ledge 258 which presents a flat surface 262 parallel to shelf surface 234 of the base. Thus in the event of failure of the primary securing means, the surface 234 of the base firmly engages the parallel surface 262 of the point to prevent the separation of the base and the point.

I claim:

1. A dipper tooth assembly comprising an individually reversible base, an individually reversible point, and means to secure the point to the base, said base comprising spaced rearwardly diverging jaws merged at their forward end to form a wedge shaped nose conforming to the contour of a worn dipper tooth, said nose having forwardly sloping lower and upper surfaces and spaced substantially parallel side surfaces, and a forward edge surface formed by the merger of the upper, lower, and side surfaces, said forward edge surface being substantially semielliptical, as seen in plan, and substantially arcuate as seen in side elevation, shelves recessed from the upper and lower surfaces and presenting spaced substantially flat top and bottom surfaces parallel to each other and to the transverse center plane of the base nose, said top and bottom surfaces being disposed centrally of said nose, as seen in plan, said point being substantially Wedge shaped and having a cavity therein shaped to complementally receive and engage the nose of said base, spaced ledges in said cavity presenting substantially flat surfaces parallel to the transverse center plane of the base nose and to the corresponding top and bottom surfaces of the shelves of the nose and in vertical alignment therewith, said fiat surfaces being spaced from said top and bottom surfaces, said base and said point having coaligned slots, and means positioned in said slots to secure said base and point in telescopic engagement with each other.

2. A dipper tooth assembly comprising a base and a 7 point, and means to secure the point to the base, said base comprising a wedge shaped nose, said nose having forwardly sloping upper and lower surfaces, substantially parallel side surfaces, and a forward edge surface, said forward edge surface conforming generally to the contour of a worn dipper tooth, said forward edge surface being substantially semi-elliptical, as seen in plan, and substantially arcuate, as seen in elevation, shelves set in from the upper and lower surfaces of the nose presenting spaced fiat top and bottom surfaces parallel to the transverse center plane of the nose, said point having an outer surface and having a cavity presenting a forward inner surface parallel to said forward edge surface, and a pair of flat surfaces parallel to and disposed adjacent the flat surfaces of the nose.

3. A dipper tooth assembly comprising a base and a point, and means to releasably secure the point and base in telescopic relationship with each other, the point having an outer surface and having a generally wedge shaped cavity therein entirely enclosed except to the rear, said cavity having a concave forward surface which is generally semi-elliptical, as seen in plan, and generally arcuate, as seen in side elevation, said cavity presenting spaced top and bottom flat surfaces parallel to the longitudinal transverse center plane of the tooth, said base including a forward nose portion received entirely within the cavity and presenting a forward surface parallel to the forward surface of the cavity, and a pair of upper and lower flat surfaces parallel to said top and bottom surfaces for engagement therewith in the event of failure of the securing means.

4. A dipper tooth assembly comprising a base and a point, and means to secure said point to said base, said base having a wedge shaped nose portion the forward edge of which is generally semi-elliptical, as seen in plan, and generally arcuate, as seen in elevation, said nose presenting recessed substantially flat spaced surfaces parallel to each other and to the longitudinal center line of the assembly and being disposed substantially centrally thereof, said point being substantially wedge shaped and having a cavity adapted to telescopically receive the nose portion of the base and presenting a forward surface parallelto the forward edge of thenose portion, and spaced flat surfaces parallel to each other and to said spaced surfaces on the nose portion, said nose and cavity flat surfaces being adapted to maintain the base and point in engagement with each other in the event of accidental release of said securing means.

5. A dipper tooth assembly comprising: a base member having projecting from its forward end a generally wedge shaped nose with a pair of forwardly converging upper and lower surfaces, a pair of spaced side surfaces, and a forward edge surface formed by the merger of the converging and side surfaces; a generally wedge shaped replaceable point member presenting an outer forward cutting edge and having a partly enclosed generally wedge shaped pocket open only toward the rear of the point member, said point member presenting in said pocket a pair of forwardly converging upper and lower surfaces, spaced side surfaces, and a forward edge surface formed by a merger of the pocket converging and side surfaces, the converging surfaces of the respective members being parallel to each other for mutual engagement when the members are assembled in telescopic engagement with each other with the nose received within the pocket, the side surfaces of the respective members being generally parallel to each other, and the forward edge surfaces of the respective members being generally parallel to each other and being generally semi-elliptical as seen in plan and generally arcuate as seen in elevation to conform in contour to the general wear pattern of dipper teeth so that as the forward cutting edge of the point member is worn away by normal use its contour will approach parallelism with the forward edge surface of the pocket; and removable means for retaining said members in telescopic engagement with each other.

References Cited in the file of this patent UNITED STATES PATENTS 916,271 Conibear Mar. 23, 1909 1,783,350 Watts Dec. 2, 1930 1,856,930 Robin May 3, 1932 2,148,925 Bochy Feb. 28, 1939 2,251,169 Seal July 29, 1941 2,603,985 Vidmar July 22, 1952 

